For those who don't know, Johnk has tried/built every overdrive under the sun and this circuit is one of his very favorites. From what I understand, it's a variation of the classic Tube Sound Fuzz/Greed Tone Overdrive design, but with a lot more to offer.

Here's what Johnk has to say about it:

This CD4049UBE based distortion doesn't eat up all your low end and tracks great with either a pick or your fingers. It can be used as a clean boost by running the gain at the minimum (fully CCW), if you just want to drive the front end of your amp to get it's natural distortion. It can also go from a mild overdrive to full out high gain distortion. The circuit in this one is point to point. There are two foot switches. The one on the left turns the overdrive on and off (as indicated by the center blue LED. The one on the right is to boost the signal even more as indicated by the 'more/less' LED (green=OD & red = boost). To make the pedal even more versatile, I've added a 'starve switch' which 'roughs up' the character of the pedal and makes it sound even 'fatter'. This 'two knob' pedal is about as simple as it gets to get a HUGE overdriven bass tone in seconds.

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This one also include the three way toggle switch ($20 option) and a lo-boost switch; low end loss isn't even a question with this guy. The picture shows the pedal with the stock chrome knobs, but I replaced them with black Davies #1510 knobs because I needed to be able to look down and see exactly where my settings are at; both sets will be included.

Only around 10 of these were made, so they don't show up too often! Can do anything from light overdrive to full-on blown tube amp sounds, all while remaining amazingly transparent. It has a way of bringing the fury while leaving your tone uncolored. Want a light OD to push a tube amp into light breakup? No problem. Got a P Bass? Crank the gain midway, hit the MORE setting and Starve switch and BOOM, you'll think Geezer Butler is in the room.

So why am I selling it? This pedal sounds HUGE, but I have a modded BOSS ODB-3 which just works for the overdrive sound I need with my current project, even though it colors my tone and loses a bit of low end. If I could, I'd just sell the ODB-3 and keep this, but alas, I need to raise some funds as I'm starting school for my EE degree this fall and need to pay my entrance fees.

I'm letting this go for $190 shipped CONUS. I do need money, but I will consider all trades, just send them my way, who knows, I could really need it! Worst I'll say is no.